914-6, mostly stock, runs perfectly on the gas. When lifting off it pops a little, sometimes, not every time. When going down hill with no pedal, no gas, it pops like crazy, almost like a backfire. New plugs, wires, points, etc. Timing seems OK, valves adjusted exactly...what else could it be? It's probably something simple I'm not thinking of or maybe something major? Appreciate any insight- thanks.

Air leaks around the intake or exhaust.

My vote is for intake leak.

Just had Webers rebuilt with all new gaskets but I'll double check everything. Thanks.

May not have them tightened down to the manifold.
Go re-tighten all the bolts that were off for the rebuild.

Rich

Another project for tomorrow- can't wait! thanks

My vote is for the carbs being too lean. Richen up the fuel mixture...

I was infested with motor popping on decel, checked all elect, valves,even

adjusted valves over and over they were always good. Checked for vac.

leaks all OK. I found my carb linkage was closing down one bank of motor

1st and they were not adjusted perfectly. I have a 4 but look at this on

your motor, linkage adjustment solved my problem

Can't wait to try all these remedies- after years of new cars, it's really fun to have an old car with an assortment of maladies waiting to be fixed. As soon as i can get out to the garage, I'll get back---

I vote for the rich mixture and/or exhaust leak...

I had the same exact symptoms on my /4, it was an exhaust leak. That's an easy one to check for too...start your car, block/cover the tail pipe, listen for hissing. If you don't hear anything and your engine stalls you can probably cross it off the list.

In my case, one of my heat exchangers was damaged inside the clamshell. Given what HEs for a /6 cost, if you can even find a set, I hope that's not the case for you!

More things to check- thanks! Can't get to it until Friday- too many root canals to do...